he outer layers of the stem.
These threads interlace to form a delicate membrane, known as the
_veil_, which closes the gap between the stem and pileus and covers over
the young hymenium.

The veil remains firm for a time, but it is finally torn by the
expanding pileus, and its remnants persist on the cap and stem in the
form of various appendages, whose character depends on the character of
the veil. In _Cortinarius_ the veil is made up of delicate threads
extending radially from the stem to the margin of the cap without
forming a true membrane. From its resemblance to a spider's web such a
veil is said to be _arachnoid_. At maturity mere traces of it can be
found on the stem. In many genera the veil consists of a delicate
membrane which tears away from the stem and hangs in flakes to the
margin of the pileus. In these cases the veil is _appendiculate_ (Fig.
248). Frequently it is so delicate that no trace of it remains on the
mature plant. Where the veil is well developed it usually remains on the
stem as a _ring_ or _annulus_ which becomes free and movable in species
of _Lepiota_ (Fig. 242) and _Coprinus_, or forms a hanging annular
curtain in _Amanita_, or a thick, felty ring in _Agaricus_, etc. In some
plants (species of _Lepiota_) the annulus is continuous with the outer
cortex of the stem, which then appears as if it were partially enclosed
in a sheath, with the annulus forming a fringe on the upper end of the
sheath, from which the apex of the stem projects.

No reference is here made to the _volva_, which encloses the entire
plant, and which is described in connection with the genera in which it
occurs.

The few typical characters described here will help the student to
become familiar with terms applied to them. In nature, however, typical
cases rarely exist, and it is often necessary to draw distinction
between differences so slight that it is almost impossible to describe
them. Only by patient study and a thorough acquaintance with the
characters of each genus can one hope to become familiar with the many
mushrooms growing in our woods and fields.

CHAPTER XXIV.

ANALYTICAL KEYS.

By the Author.

CLASS FUNGI.

SUB-CLASS BASIDIOMYCETES.[F]

Plants of large or medium size; fleshy, membranaceous, leathery, woody
or gelatinous; growing on the ground, on wood or decaying organic
matter; usually saprophytic, more rarely parasitic. Fruiting surface, or
hymenium, formed of numerous crowded perpe